Tread crank mechanism, particularly for cycles



Aug.' 10, 1943. F. UENHARD TREAD CRANK MECHANISM, PARTICULARLYI FOR CYCLES Filed Jan. le, 1941 4 sheets-sheet 1 Aug 10, 1943- F. Ln-:NHARD 2,326,235

TRED CARANK MECHANISM, PARTICULARLY FOR CYCLES Filed Jan. 1e, 1941 4 sheets-sheet 2 Aug 10 1943- F. LIENHARD 2, 326,235

TREAD CRANK MECHNISM,` PARTICULARLY FOR CYCLES Filed Jan. 16, 1941 Fig 4 Sheets-Sheet 3 Aug. 10, 1943. F. LIENHARD 2,326,235

TREAD CRANK MECHANISM, PARTICULARLY FOR CYCLES l Filed Jan. 1e, 1941 4 sheets-'sheet 4 f fff 2,226,213#

Fritz Lienhard, Zurich, Switzerland, assigner to Magus A.' G.,"Zurich, Switzerland, a corpora` Application January 16, 1941,1SeriaiNo'-r3 'j In VSwitzerlandMarch 26, 19403v s The Apresent invention relates to'improvements ZIII'I, which' results inthe,.advantagefas ccnifintread crank mechanisms, particularly` for -pard1to thefcircularftread-pathg'that'thejangle I cycles. i l ofthe-knee 'andthede'BeXin f'thefshank of Y y'posed in order t5-adapt Vthe'treadcrank mechexertion to provides, design offs'aid mechanism also a,reductionof,.'the' xtension Vand c ofrnpres'- ,in such .a mannerthat the path ofthe pedals, sion ofthe musclesandtendonsWhichlenhance llinear. shape, i. e. aless'orlmore attened curve, 3 inthe kneeLAsa result',l,theextreme angles'bf lsothat the mtionjof the legs is transformed into thefj knee becmefreduced infvalue as' clearlyv Y. Y an up"andfdownw'ard motion.v HoWever,;-as a shown in Fig- 2, 'In'saicli figurethe dotted lines consequence ofthe-abrupt inversion of motion show .theextreme positionsl ofthef legfor `laciri vkind resulted in'undesirable accelerating and reof Ythelegv when 'the'tread path isla"furvfe lyi jfatigue in'spiteof the highereiiciency' much '2O tiallyofa constant'value'jand'fdoesnot'undergo more rapidly. It is to benoted that the human va Vmodicaticn. 'from thestretchedlpsition toan f legs yare no metallicconnectins-rcds there is a excess] 'acutei angle 4"ijn ajmanner' to lproduc :an

lack of the rotating mass which is required by y over Vevery crank mechanism in order 'to .assist by. .lation means of the stored up energy in'overccming the' 25 form oneland.y the lesr Yorga'r'lism'` is'not in'uen'c'ed f v'deadcenter positions. .Hence it isnot suicient bythe successive changes ofvaccelferationandfres f' same time this mechanism must be adapted to rangement extends froman'upper anterior'point Y vthe following explanations.`

Various `arrangements have already been'prothe cyclistbecornes considerably reduced from .1

fthe' point Ito point IlIjand backwards, andasa s anism. especially ofcycles to theconditions Yand consequence thereofthereV is not only obtained thepeculiaritybi theflegs and their muscular a better-:eciency,inthe*mechanical sense,.but

vinstead of being la ,circle,1 approaches a vmore 10 considerablythe`jfatigue aslwell asthestrans at the ends of the curve, the mechanism ofethis l5 ,cularj tread path 'andv thefull lines'the Vpositions tarding eie'cts',which produced particularly at inf the directionofthefdagonall-IH.'.lilrtli' g f the ascending pedal adisturbing impact on the `more thisY gure 'shovv's that `the fang'leat thel f sole of thejfoot'ol? thejcyclist, soas to `produce V knee remainsduringthe tread''motifjr'il'substanf-v Y to improve these conditions by mechanical moditardationllf;

cations of the crank mechanism,` `but at the Asth' general'direction'cffnictionin'this-.ar--" the peculiarities of the leg motions as set out in 30 toanV under posterior point'With incliizlation y 'of 15 -7 5 te' the herigqntai, theresultinggkindf In dividing'the leg moti-on exerted during the A not motion .and force eiect'of the legs isnfefaljlyj drive of the rotating pedals in four sections cory like that exertedwhen'jumping,` 'hence a' riatresponding t0 the quadrants I-v-I I, II-'JIL ural operation, ,whilst the hithertouSedcircIilar' f III-IV and IV-I oiV the circle C 1afs illustrated 35' path ofgthepedal treading requidpa increcr4 'I A i' inFig, 1, the vectors being inclined under 5 less artificialandtherefcre foced'asaptatinof" the'arrowp:

to the horizontalline, fthefcllowing phases of the organsto Vthe meQhanismLft the .l Y motion occur when m-ovingin the direction of same time,Y thesaid"arrangement'permitsnlso Van Vincrease of .the effectiveQtread Vstroke` byla ,i 1". The downward phase I-II substantially pro- 5 40 prolongation of ,tl1er tread' crank arrn, L as shofvvn'yV @luces the driving force; 2. Thelbackward phase yin .dotted'linesfin.ig.f1, so lastojprof' Ill-III is for'the strokeinversion.` The'upduce V'a ,considerable'increase ofgyoutputrwthoutc j L' 'Wardr .phaseIII-IV ns1;V only dlofe'gliiotproduce any increase of thevangleggo'f-the kneeideezgion.

- and 4 The forward phase 1V I1, frthretmke y Y:eur inthe shortinstaritvinflwhiehthe 1ngitdiany driving forceubut produces rather a braking Of-courseit is ofhi'ghimpcrtance fthatasfafcrle; eect, particularly whenthe cyclistl s ifaigue'd; 45 I fnentionedV the inversion o ff' motion doesznot ocr inversion.

, 4 e ,e y nal axis yof the'pedal arms arein alignment,ibut It `is obvious that in; order'to. obtain aflrine-y that theconguration of,thetrcadnathjisfsuch` l matic improvement andparticularlyan A'aclaptathatlin said. alignmentv position therefesultg a' n Y *tiofto theifstructural organization cftheflegsfQ-mre OITSISSSsmoothrtansitionfromnedirection .whenjumping the'phases ll` and' Il m'u'st'fpsvganlsrn "can adaptfitself' Withoutany 'forcafscf n must take place substantially albngltheffully mechanical andgthe'human I riotive,orga1j1s. v

viniendo likewise not'performacircularmction olfmotiontqthe otherfof whighthe:musc1e-or.; sibly be'eliminatedV andhencefth'eYtreadm-tion` as to obtainalperfect synchronismbetween-th f shown curve in the direction or theuiagenl 55 Theaforslaii' desiderata arer'eanzed' with' h c. 1

tagliente 'dtingftiie drive;

l Figlriifshowse riewiriiete izeietotioneoei A2,326,235' Y Y n tread crank mechanisms, according tothe inf Fig. 10 ata smaiier scale the arrangement of vention because both tread cranks are journailed each separately by means ofv diametrically op.

posed' pivots in a rotor element,- which is rota- .torily supported in a bearing element secured Y in thefcycle YVframe and.'correlated to th-e pivots vof theytreadcranks y by means of transmitting x l .Y elementsaing'silchaway; .-that}the two pli/'cts of i 'Referring no the said mechanism in-acycle.

characters o fv reference designate similar parts Y in the various views, Ythe tread crank mechanism according to vthe rst embodiment iiiustrated in Figs VI5-v1.5; coniprises a wheel shapedY bearing elethe tread'lcranks vwhen driving the pedals rotate together withjsaid rotor velementaround.A its axis;

of rotation insuch amanner, that the path o greater axis of which is therear. 7. l j This connecting ymeans cogli realised asis mechanism known under this designation of .will be used, the planet `wheels'offwhich meshing rwith stationary internal teeth .rims are frigidiy 'connected' with said tliii'nioris'V of the `tread-lcr nks and the Wheelsuppfirt of whihjorrns Vthe rotor:eieineot'eoooeeteowit be competitie .iie and the beekwheel of thetovole owfevei the seid .eooiiteritionei .designs eesiirfioe realizes in e chais is .ron-

Wiieel .of the-'reet {Wheei 'asie 'in @tittiesmeisii-V f riiis eirsloseiiieot.oiieistiie' .further advantage .thotltiie rear wheel may roe toison oir ano ser offeiii e off. i

` be provioeoenoloiine-a veria tios oi tiiejsree't oi the path of 'tie pedals' 'in' order tof eoeottliesaiof-inf olinatio al reouirexrintsof `.tloe' f course a driving mechanism of thegfgresaid arrangement,mostootbeosesi merely for Cycles,

general foi# all. treed eratiklmei n isms,

e drive of fans etc. i f

tion,-

the obieotof, the inventiongalre iiiist a ism in Iam eievae Fis.; 3 agjtread eranlsmecii onview;

i nissan @smalley sqaieithe v mechanism inalc'ycle;

menester' 1 through itl-ieY oeotfol' axisofthe;treadrbearins ,--ozsie of;feoother'emnodimenti oi tne'fmvention,l

:iienmustratesamuser embodiment sfthey invention, the 1e ftfha.lfjshowinga view ineleva-'f Ationfandthe'rightrrhalffavieiir invertical-section through the @ennemies esorosket wheel;

ies euliey ansehen v Li'romthis with its iowesoraooh"overthesproolset e d. and effect tightening oiitiieseiieiri 'by t e eiteretioooieo otrv designation eAliilliLeiLis,i tobe under- Y everyV` Closed oval curve eveniif itl does not sposo inf all. its parts .to the ellipse -eooae the ymotion of said 'pedals 4forms an ellipse, the A inclined downwardly'to :means'of'ballbearings 2 and a iit bushing the v Y rotor veleynient 4 composed of two halves. v Thev twghalvesg and 4b of'said rotor element are*v centred by meansoi do-Wel pins 6 and fastenedA togetherpy Ineens of screw bolts with nuts.V I

crank-'loon but preferabiy a planetary wheel'gear Vment VI .rigidly'lsecured in the cycle frame,- the traineV tubes vRi and R2 (Fig. 5) as Wellv as the nl iioefthefbearing element i is journaiiedby to permit einem fission h'oe I6. The."soeei e bushing essentiel street opposed trunnions 'I on Vwhich are journalled by means oiioali bearioss the planet wheels 9- Eaciioii'saisioianet wheels !i V is meshing with an Vinternaiiy toothedfgearfrim' Iii.V The'twovgear itims i@ ere situated o o both ,sides ,of .the bearing element l 'iowhiohtheirooiiais itc are inserte@ Yv litii rusoinslfit For assembling the two' gear "rims on erlioreoisets .i5 welded (ii-.otheiwise seemedv le, tlleyiore pitovided with pairwise arranged to the rimseofl between each air oli isalrranseoeserewboit. i8, sorrourioedb through a slot io;tiiebeairiT element iii; o f, 'the rotor element @Whieh are fasterie i` to` getiierby serew toits *l2 with the inte-1539; pgp tions-taf s Y .with the rines iziitteoiintott geg?- Ci 5e respeotiveiy, oonst e together J9 lat eral ieiosores, so `tiiattiie Whole cons. utes e ".oiosed housing' viiiioheanee i iiiled witiilubrieatf los areas rines/I4- whiolo slide. on the oiroomferenee o tile' portions, lib enojo.: l r1 ioo'ss elsl of 'the rotor oorto, the rines f were inserted sealing tions 4b and 4d.areinsertedjbalilbearings .I Lin '.Whioiiar'e iourn'aiieo -theitronnioos'se' of.- the di cranks therarms o f wiioiiare seemed- Amaxwell known mamierjby means of sore?! bolts S ou the trunoioos whioiiarej fastened centrally to thesis-net wiielelsii Eoithermore, to the right, liano portion 4d' ois-the; rotor isseeored. 4the sprocketwheel H by'rneans'oiintemallyvpro# "(liigsgl and Dj' isjiixei-itothe exterior surface.

temoins. arms lia and screws lfisgjso esto rotate together with the rotor, y

11n Fie-'3, the path of motionE of the ti'eti ,Crooks e. .the pedals P, isshowniasioeins an? ellipse A.' f lhe lons o ofthe ellipse A is shown as beiner veitioaliorftiiejsake oi Afittingonthe draw: litreaily'the ariaogement in-the bicycle which is inlirielwith the'tread o ranks'et their alisneopositiomis neiined aten ongles. tothe horizontaliasshownion Fig. 5. In the present fcase this? angle"Y is 53 Adegreesrapproximately,A vIn order toyeeeooimodete the positiooof the .axis end of the Crank position to the necessities et; thecyclisrt'ioithe one hand ancijtotifle slope 'Y oithe'road onthe 0therhand, theiollowing'de vieis providediorqwas-teotheoseement le 'mon shaft 2| :ioirneiied iriel vsupport :22, vtree to .sotetethereoiii sito. Support is jiixecito theiouter vsilrtaoe o fthebearios disk la:

to the drawings in' which-iikeV rQLQreIement 4 constitutes a planet Wheel sito n Y Y "2,326,235 lShah; 2i a.' r@e1-'wheelY is also' keyeaaineshing with its mate 24, fixed on the lowerend-of avshaft V25.` This-shaft 25 is arranged inside thefrarne tube R2y (Fig. -5) and extends up -tothegfrontf ranged. similar togears-23-`24, whichpair can be rotated byrmeas of a lever 26, YAnoscilla'tingV motion of the lever; is transmitted through the` upper pair of bevel-wheels, thefshaft 25,i`the pair ofY bevelwheels 23-'24',"th`ezshaft 2| andthe 'axis Tof thepedal path inclined downward to the since: in thiscase/ equally the rotor :isV revolving Vhackwardly-a`rid thl-3 upper-branchof the chain v runs as'tern`onlaccountiof vrolling the intere' mediate chains 4l on thefiixed sprocket `wheels "G0, softh'at the treadcrankfpinsare compelledI y.

pinionsgzc and finally to uit testneu 'segments i9, so that the gear rims l can be rotated, whereby the position ofthe axis' ais' varied accordingly.V

VIhisgraduation preferably ranges thin and '(5 degrees or within narrower"limits.V

" At the rear end of the lowerframe fork Ga for guiding the chain`21, which runs lover the vdriving .sprocket-'wheel I1. VFrom the leading pulley 28 the lowerbranch of chain runs over theY sprocket wheel 3l keyed on'v the axle'A ofthe 'rear wheel lI-I. This axle isfbedded in. afdowne wards inclined'open slotf3ls of theforkjhead 3B,

so, as to automaticallytighten the chain on place ing'therear wheel.

crank mechanism is'as follows:

The inode of operation ofithefdescriheditread On treading the cranks T in the direction of l n the arrow (Fig. 3)` the planet wheelspS revolve Vin the samej direction' 'rolling' on the gear rims l leading pulleyv 28 is vsupported on the stud v29 VIl) at arateof onein two. Since the latter are` fixed'to the frame, the rotor element 4 revolves,

but inopposite direction,`i. e. backward asA shown by the-arrow. Y -Q From `these two motions resultsthe elliptical path A for the pedals P'wliichpath'at thefends of the long axle 'a allows a 'smoothV passing, freef of jerks, and for the restpthisellipticalpathincreasesjlhe eilectiverpower stroke whereas the amplitude of theVV angle of the shank,1i.-e.fof the .y

knee,` limited'by the-'short axis'vof the elliptic path, is by far smaller than in the 4ca seof .pure y Y circular motion.

4 vIn the Ycase of these-cond ernbodinient of the invention shown in Figsf and Y7; a circular supporting element 3 I, isflxed tovthefranieofcycle,

similar `to the" arrangement as described above. VIn the hub 3 I n of this supportingelenient a tread bearing axle 34 .isjournalled' on radial hall` bearings 32 and 33,'such .asto bejsecuredagainst axial displacement, The ends of this axle are fittedY with dainetrically opposed cranks 3,5, se-

cured IcyY screw wedges'zliA against rotaryv deplacement. These cranks I 355. laterally cranked. towardV the central plane, together with thev treadbearing axle rrepresent the rotrelement. Inl l,

the widenedouter end portionY ofeach crank 35 the ,treadcrank pin 38 is journalled on thelballbearingsii'l, vthe projectingouterportion,of this pin being tted with the tread crank-Tin the Y y usualway. To the inner end of each treadgcrank Y pin a Asprocketwheelll isfleyed and ingalignment with it'another sprocket wheel 40 of twice as many teeth is fixed to thehub of the supporti'ng element `sprocket chainrl as an`.intermediate'member. Thesupporting element `3l at eaoh'sideis closed by means of covers 42 and .43, -xed to the rotor.V

' Y The driving sprocket wheel. Il is xed to projectionsa and D of thecrank 35 Von the side Y ofthe sprocket wheel `byineansof v threefarms lla.

g'rne arrangement on the bicycle'issirmuarY to AThese two sprocket wheels. Sf of each pair are coupled by-mleansrofaV er diameter 'of' the" tr nient vis built up of these axlesand cranks. The' outeri andwidened'f'end'sl'of the cranksp'ig'goiset Y laterally toward* the'lfcentral'f plane,'ffarev Iittedi` y with Yball bearings 51 in'fwhich aref'journalledthe y pins' 585 of piih's'fv, andgfthe projecting l:outer -eneds Vof these' pinsare-itt`ed""witli the tread cranksT In .alignmentA lwitloffthese pinion's" 59 the projectingside endsgofthefbearing bushing Y 'i'.wice that offthe outerpihion's,-fi. e.fof"ftheiplanet '6l are enclosed-'in a' cas chainflines) .f l l Y elliptical pedal pathfA the .rear at an angle of 'frame fork, 'on -to -'the 'driven' sprocket wzneeirV 3 lf, over acflclfk its circumference.' arrangement and mode of operation as inV the aforedescribedj embodiment Yloe provided for, inwhlchcasethe arrangement' could be such;,tliatthegsprocket wheeluwithtine., Y

mechanism acc'ordinggftofthisinvention; it is possible' tdgivethefposition of thel'zwtreadjy Y Y' cranks 'a diierent angle and'theffcranks 'them-'l selvesa differentlengthfinforder to adjust the mechanismzto the"di1Terencesfl-of lthe two-legs'` in the casepfarcy'clist-having legs'of..different'A Yone crank only,` the other crankbeing YiXed-to'rr hev bearingjof Lthe,traan 'cfakjjpinnng downward- `with the last; described garanger'lertfthecutg 1 i `ad beaming is; non, erger f AI donot' limit mylginv'entionV tothe structurs' than thatcf the treadbanng as" use f Forj' the {restftl'ie.`

j sirmila'r; Y Instead of but one intermediateineinber,aplurality can` shormsand; described. gasimodeations; within 7 3.- Inatread crank. echanis .the scopa o-fithc apnendedaclaims maybemade without departinsfiromthe. spirit; oifjmv ini/enf` desi t --secureby VLetters Patent is: 1

vfor cycles, thoccmbinationg cmprisingfa bear.-

= .in'eelementmountedthe; cvleframe, a rotor alimentan .what

fen

. element -rotatively mountedeinsaid;bearing ele- 'ment a. pariof opposed iournals-1ooated-n Said .l rotorev eherxwrltifyaV tread crank having a ypedal Alow/ing;- a'haftJooatedin each pfsaid journals, aaplanetavmemberfxed' toeach shaft, transf mittmsmeans interposed. between.. .each .plan- V starr; mamier.'t1-11d.-- Saidfsrotor element and a sprocket wheel fnxedV to said rotor element. for .Qdrivi glthe'cyclewhereby'upon rotationpf said tread lcranks and rotor element the=peda1$ LIPOH Saidtredfstankawillsiescribaan elliptical. path haring .the maior-axis thereof inlned v.downfonoyoles, ti'iecombination comprising a bearingelement mountedinthemcyole frame; agrotor j i element rotatively mcmnted i111said bearing elej nient, a-pairof opposed journalsylocated in said Y rotorfelement, atreadcran,k having fa.- shaft ,locatedfinfeach Vofsaid journals, ya Vplanetary member Vfixed to'. eachl sliaft; VAaV -pair of fixed facaaaa iorcvcleal-thcsombination comprisinga bearing elementmountsdin the-cvclegfame, a rotor `element rotatively mounted .in ysaid bearing ele,- ment ,a pair of 'moposed journals located in said rotola.clement,V artreadi crank ghavingra shaft located in y,each of; said journals@l a planetary member ied tofeachshaft,Y a pair. of rotative.- ly. adjustable internal gears.. cooperating with A. s aid planetary. neIIIJOers;I a Sprfooket Wheelhgied l. to lsaid rotorlfelement and means t cooperating.. with said sprooket. .wh eel:.for .driving thecyclei 6. In a vtread.crank mechanism, particularly vor cycles, tliie combination comprisngag'bearine: element mounted inthe cycle .f1-"ame, .a rotor element rotatively mounted in said bearing element, apair' of `opposed.journals.locatedin 'said'rotor elemenn atreadcrankV havingy a shaft locatedginfeach of;.fsaid journals,` aplanetary I'Iieinlifeifiixed toI eaphhaft, a pair vofzrotatii'zely' adjustable internalgears cooperating with Y 'said 'planetary .membersa sprocket Wheel vfixed internal" gears A.cormerating with said planetary 1 @lem man@meansfcoopereting.with saidjsprocki- Y et wheel [for drimn'g. the cyele.

inent, a fp'a'irfof opposed'journals located Vvin said hub YVofisald bearingelement,means securing i Sadjportions togethergandeach jofir-saidgpor-f tions comprising an outer. disc;v a, ring` tightly contactingtheladjacent internal gear 'and a packiif." jr.ing. associated with.vr aidlirst mentioned ringforniing. a sideclosuresothat a closed cas-Y ;ing islforfnied.. V

:Ina tread crnkmecnanismj 'particuiariy forj cycles; the combination comprisingvpa bearingelement Amounted inv the cycle! Vframe, a rotor element rotatively Vmounted in said bearing ele-V ment, aparirV of;opposed-journalslocated,in said rotor element, a.'tread-crar1l\:--A having ajgsloaft loo'atedin-.acn of .said 'journalsfa planetary member f-fixed to leach..` shaft,y 1a, pair. of'iii-xed 'inlV o ternalqgears cooperatingA withV said planetary menthers,.a sprocketzwheel 'iixedl'tovsaldi.'rotorV elementgrneans cooperatingzwith" said Y sprocket wheel v tdr. driving I the cycle, :said rotor' element l' ing element mountedin'tliecycle VframesetA rotor )clement rotative1y.;mounted in said bearing ele- Y to" saidrotor element, "meansjfco'operating:With l .said sprocketjwlieelicr driving- .the cycleq and means for securing said. adjustable internal gears 'lllngatrea'd crank'mechansm, particularly for cycles, "thefcombin'ation comprisingabear.-

ing lelerrientlmounted in theA cycle frame; a rotor element' rotatyely'mounted in I said bearing jele.-

mrt; af pairj offoppsedjournals located fin said rotor element, 'atread'crank having a'jsharft 1o- Cated in each .of said journals,aplanetarymember xedtojeach shaitfla'pair of rotatively ad.-

justable internal Kgearscooperating With said Vplanetary rnnenilbers;a4 .sprocket Wheel fixed to said Vrotor,e1enoer1-t meanscoooeratinawith said sprocket Wlfieelor` drivingY the cycle, said. ade juvstable internalfgears'nhavingy toothedy segments upon their exterior"peripheres,pixlonszmesh- .ing withj'said segments; a shaft, apirii'on.j upon said shaft for driving'said pinions 'sof that upon `rotation o ff said shaft said. internal gearsmay be' adjusted `with` relation to' saidfbearing ele- 'I Y travelV ofthe pedalsjmaybe varied.

' memberxed to each shaft, transmittingineans yinterposed between each planetary membelancl fo1` WQlSf the' 'conibinationv .comprising a4 bearing element mounted in the cycle frame, va rotor element rotatively mounted in said bearing ele#V ment Ya pairofoppedyjournals v.located in said rotor' element, a treadV crank having a shaft located in each'of 'said journals, a planetary saidrotor elementtand a v.sprocllzet Wheel-fixed rGO comprising ftwo portions journalfled'; in "the lhub ofjfsaid'- bearing Y'element@Yv means.; securingV said 1 portions .togetl'ier and each 0f. Said portionsY cornprisingjanjouterj disc', a ring tightly contacting theadjacet internal fgearL apaclnngring associ' todi-With Said first mentioned ringforming Side Closure S0 iliataelsed; tasingisiformed tofsaid` rotor? element for'jdrvingQthe cycle Vwhereby upon rotation of,v said tread, cranks and Y rotor element thelpedals upon said treadV cranksv willv describe an ellipticalv path having the ma-A jor axis'thereof inclined downwardly and rearw'ardly," agsecond sprocket vvloeelV fixed to the shaft of. 'theA driving V.wheel ofvsaicl cycle, a

.sprocket chainfcooperatingfvwith.both of said 4sprocketwheelsy a leading pulley for saidcloain over` Awhich said sprocket chain passes so the loWerl stretch. of` said :sprocket vchain Inay coopcrate .with :said sprocketl wheel Vupon the' shaft of `said driving wheel. I i j p Y 9. .InV a :tread crank mechar'lism,V particularly for cycles,l thev combination comprisinga bearingr Velement mounted in the cycle frame, a rotor. element rotativelyn mounted `iii-:said .bearing ele- 'Y bearing element and element.y t V j 12; In a tread crank mechanism,'particularly ment, a pair of opposed journals,ilocal-:ed in said rotor element, 4ak tread kcrank having a pedal having a shaft llocated in ,each of 1 said journals, a planetary member 'iix'edlv to eachv shaft, transmitting means interposed rbetween eachV planetary member. and said rotor element f and a sprocket wheelxed to saidjrotor element Y' of tread. cranks, lshafts for said treadV cranks `rot'ativelyimountedin said V-flrst mentioned cranks,

. means interconnecting said'sh'afts and saidl gears.

upon *saidbearingjelement, a rotor arm fixed'y )to` said Vaxle and having one end rotatively downwardly and rearwardly, said transmi tingmeans comprising coacting gears.

10. In atread crank mechanism, particularly for cycles, the combination comprising abear-l ing element mounted in the cycle frame, arotor element rotatively mountedV in said bearing element, .acpair of opposed journals located Y pedal havinga `shaitvlocated in each ofsaid journals, a planetary member fixed to each shaft,

transmitting means interposed between .Y each c planetary member and said rotor Yelement and a `sprocket wheel xed to said rotorl element for driving the cycle whereby uponrotation of said tread cranks and rotor element the pedals upon said tread cranks will describe an elliptidownwardly anad rearward1y,\said transmitting means comprising sprocket wheels fixed to Vsaid bearing elementrand sprocket chains cooperV ating with said planetary members and saidlast named sprocket wheels.

Vin said rotor'element, a'tread crank having a l means interconnecting'saidshaits and said gears upon said bearing element,a, rotor arm fixed i to said axleandfhaving one` end 'rotativelyj,. v mountedrcongcentricllto 'one ofjsaid lshafts',afv

cal path having the major axisthereof inclined l11. In a tread crankinechanism, particularly for cycles, the combination comprising av bearing element mounted in the cycle frame,`a

rotor element rotatively mounted-in said bearing element, a pair of opposedjournalslocated.V

in said rotor element, a tread crank Y,having a' pedal having a shaft located in eachgof said journals, arplaneta'ry member ixedv to each shaft,

transmitting means Vinterposed between each planetary member and saidirotor element and e a sprocket wheel lixed to. said.VV rotor element for drivingA the cycle wherebyupon vrotation -of *i said tread cranks and vrotor element the pedals upon said tread cranks will describe an elliptical path having the major axis thereof inclined downwardly and rearwardly, covers xed to the tread cranks, cooperating covers ixedj` to .said

rotating with saidcrotor mounted concentricto one of` Vsaid shafts,Y a v ly "for cycle'sthe combination comprising'anbear-Y ving element formed asa' cylindrical bushing rigidly Xed vin 'the cycle frame, gears Xed to said bearing' element, a: tread bearing Vaxle rotatively journalled inisaid bearing member, opposite- V1y disposed-cranks lixedV tosaid axle,'a pair ci tread cranks, shafts florisaid tread cranks Arotaf'k tively mountediinlsaid first mentioned cranks,

sprocket wheel fixed to said arm, means Afor and said gears comprising planet wheels upon eachlshaft yhaving vone-halfxthe diameter of said l gears and pinions V`interposed between said planetV wheels and saidggears; said pinions being* jour'- L nalled on said lirstmentionedcranks. Y 14.7In a tread crank',mechanism,jparticularly for cycles, the Vcombination` comprising abear f f ing element formed as Vafcylin'clrical'loushing rigel vidly xedin 'thejcycle" framagears Iixedto i said bearingf element, a tread bearing axle vrotatively journalled'to said/bearing member; oppo-V c sitely disposed crankrfixedto said axle, va pair y of treadv cranks, shafts Torf-,said treadcranksy 4 rotatively mounted in said first mentioned'cranks, means interconnecting said shafts andsaidgears l .upon said bearing elementari arm fixed to said axle and haVingone end rotativelyV Vmounted f' concentric Yto one of,Y said shafts,- a sprocket j` c Y wheel fixed tosaid arm, ,meansfforfdrivingthe'V cycle cooperating `withpsaid sprocket wheel, said y means interconnecting'said shafts and said :gears if' ing one-'half the diameter of said gears and pin-` for cycles; the combination comprisinga bear-lj` Y ionsV interposed between v'said planet wheels 'andy 1 Fsaid gears, said pinions being` journalled onsaid Vfirst mentioned cranks and a .casing enclosing y,

said planet wheels, pinionsjand gears.r

cycle c cooperating with said 9 

